Implement alert_endpoints and http_lint plugin extensions

Alert endpoints can now be loaded via custom plugins.
It's now possible to extend the http_lint parameters with custom parameters and validators.

scripts/plugins/webhook_alert_endpoint/alert_endpoints/webhook.lua

@@ -0,0 +1,173 @@
+--
+-- (C) 2018 - ntop.org
+--
+
+require "lua_utils"
+local json = require "dkjson"
+
+local webhook = {}
+
+webhook.EXPORT_FREQUENCY = 60
+webhook.API_VERSION = "0.2"
+webhook.REQUEST_TIMEOUT = 1
+webhook.ITERATION_TIMEOUT = 3
+webhook.prio = 400
+local MAX_ALERTS_PER_REQUEST = 10
+
+-- ##############################################
+
+function webhook.sendMessage(alerts)
+  local url = ntop.getPref("ntopng.prefs.alerts.webhook_url")
+  local sharedsecret = ntop.getPref("ntopng.prefs.alerts.webhook_sharedsecret")
+  local username = ntop.getPref("ntopng.prefs.alerts.webhook_username")
+  local password = ntop.getPref("ntopng.prefs.alerts.webhook_password")
+
+  if isEmptyString(url) then
+    return false
+  end
+
+  local message = {
+    version = webhook.API_VERSION,
+    sharedsecret = sharedsecret,
+    alerts = alerts,
+  }
+
+  local json_message = json.encode(message)
+
+  local rc = false
+  local retry_attempts = 3
+  while retry_attempts > 0 do
+    if ntop.postHTTPJsonData(username, password, url, json_message, webhook.REQUEST_TIMEOUT) then 
+      rc = true
+      break 
+    end
+    retry_attempts = retry_attempts - 1
+  end
+
+  return rc
+end
+
+-- ##############################################
+
+function webhook.dequeueAlerts(queue)
+  local start_time = os.time()
+
+  local alerts = {}
+
+  while true do
+
+    local diff = os.time() - start_time
+    if diff >= webhook.ITERATION_TIMEOUT then
+      break
+    end
+
+    local json_alert = ntop.lpopCache(queue)
+
+    if not json_alert then
+      break
+    end
+
+    local alert = json.decode(json_alert)
+
+    table.insert(alerts, alert)
+
+    if #alerts >= MAX_ALERTS_PER_REQUEST then
+      if not webhook.sendMessage(alerts) then
+        ntop.delCache(queue)
+        return {success=false, error_message="Unable to send alerts to the webhook"}
+      end
+      alerts = {}
+    end
+  end
+
+  if #alerts > 0 then
+    if not webhook.sendMessage(alerts) then
+      ntop.delCache(queue)
+      return {success=false, error_message="Unable to send alerts to the webhook"}
+    end
+  end
+
+  return {success=true}
+end
+
+-- ##############################################
+
+function webhook.handlePost()
+  local message_info, message_severity
+
+  if(_POST["send_test_webhook"] ~= nil) then
+    local success = webhook.sendMessage({})
+
+    if success then
+       message_info = i18n("prefs.webhook_sent_successfully")
+       message_severity = "alert-success"
+    else
+       message_info = i18n("prefs.webhook_send_error", {product=product})
+       message_severity = "alert-danger"
+    end
+  end
+
+  return message_info, message_severity
+end
+
+-- ##############################################
+
+function webhook.printPrefs(alert_endpoints, subpage_active, showElements)
+  print('<thead class="thead-light"><tr><th colspan="2" class="info">'..i18n("prefs.webhook_notification")..'</th></tr></thead>')
+
+  local elementToSwitchWebhook = {"row_webhook_notification_severity_preference", "webhook_url", "webhook_sharedsecret", "webhook_test", "webhook_username", "webhook_password"}
+
+  prefsToggleButton(subpage_active, {
+    field = "toggle_webhook_notification",
+    pref = alert_endpoints.getAlertNotificationModuleEnableKey("webhook", true),
+    default = "0",
+    disabled = showElements==false,
+    to_switch = elementToSwitchWebhook,
+  })
+
+  local showWebhookNotificationPrefs = false
+  if ntop.getPref(alert_endpoints.getAlertNotificationModuleEnableKey("webhook")) == "1" then
+     showWebhookNotificationPrefs = true
+  else
+     showWebhookNotificationPrefs = false
+  end
+
+  multipleTableButtonPrefs(subpage_active.entries["webhook_notification_severity_preference"].title, subpage_active.entries["webhook_notification_severity_preference"].description,
+               alert_endpoints.getSeverityLabels(), alert_endpoints.getSeverityValues(), "error", "primary", "webhook_notification_severity_preference",
+         alert_endpoints.getAlertNotificationModuleSeverityKey("webhook"), nil, nil, nil, nil, showElements and showWebhookNotificationPrefs)
+
+  prefsInputFieldPrefs(subpage_active.entries["webhook_url"].title, subpage_active.entries["webhook_url"].description,
+           "ntopng.prefs.alerts.", "webhook_url",
+           "", nil, showElements and showWebhookNotificationPrefs, true, true, {attributes={spellcheck="false"}, style={width="43em"}, required=true, pattern=getURLPattern()})
+
+  prefsInputFieldPrefs(subpage_active.entries["webhook_sharedsecret"].title, subpage_active.entries["webhook_sharedsecret"].description,
+           "ntopng.prefs.alerts.", "webhook_sharedsecret",
+           "", nil, showElements and showWebhookNotificationPrefs, false, nil, {attributes={spellcheck="false"}, required=false})
+
+  prefsInputFieldPrefs(subpage_active.entries["webhook_username"].title, subpage_active.entries["webhook_username"].description,
+	     "ntopng.prefs.alerts.", "webhook_username", 
+             "", false, showElements and showWebhookNotificationPrefs, nil, nil,  {attributes={spellcheck="false"}, pattern="[^\\s]+", required=false})
+
+  prefsInputFieldPrefs(subpage_active.entries["webhook_password"].title, subpage_active.entries["webhook_password"].description,
+	     "ntopng.prefs.alerts.", "webhook_password", 
+             "", "password", showElements and showWebhookNotificationPrefs, nil, nil,  {attributes={spellcheck="false"}, pattern="[^\\s]+", required=false})
+
+  print('<tr id="webhook_test" style="' .. ternary(showWebhookNotificationPrefs, "", "display:none;").. '"><td><button class="btn btn-secondary disable-on-dirty" type="button" onclick="sendTestWebhook();" style="width:230px; float:left;">'..i18n("prefs.send_test_webhook")..'</button></td></tr>')
+
+  print[[<script>
+  function sendTestWebhook() {
+    var params = {};
+
+    params.send_test_webhook = "";
+    params.csrf = "]] print(ntop.getRandomCSRFValue()) print[[";
+
+    var form = paramsToForm('<form method="post"></form>', params);
+    form.appendTo('body').submit();
+  }
+</script>]]
+end
+
+-- ##############################################
+
+return webhook
+